1. Field of the Invention
This invention is an ultrasonic Angle Beam Spectrum Analysis (ABSA) technique for differentiation of localized High Temperature Hydrogen Attack (HTHA) in welds and any heat-affected zone (HAZ) from other defects in the same area, e.g., welding defects (including porosity, slag, undercut, lack of fusion, etc.) and inclusions.
2. Description of the Prior Art
Previous HTHA inspection techniques using straight-beam ultrasonic transducers can detect and characterize volumetric HTHA in weld metal and base metal, but cannot detect or characterize localized HTHA in a weld or HAZ (weld/HAZ. See U.S. Pat. No. 5,404,754 which is incorporated herein by reference.
Prior to the instant invention, there was no nondestructive technique that could identify localized HTHA in a weld/HAZ from the external surface of a pipe or a pressure vessel.
Conventional, ultrasonic techniques using angle-beam transducers to inspect a weld/HAZ can detect localized HTHA when operated at a high sensitivity level, but cannot differentiate localized HTHA from welding defects and inclusions that are also detectable at the high sensitivity level.